[Serusers] How to avoid calling route() in a failure_route block?

I have an unusual need: If a contact in the usrloc database is unreachable for any reason, I must immediately delete it from the usrloc database. I know how to do the deletion, but I don't know the right way to write my configuration script. Below is the script that I want to write. But I think it won't work, because I think it's illegal for a failure_route block to call a route() command. (Am I correct about that?) Can anyone tell me what I should do instead of the following? Thank you in advance! Tim ============== route { [...irrelevant stuff omitted...] if (method==INVITE) { route(1); } } route[1] { if (lookup("location")) { t_on_failure("99"); t_relay(); } else { t_reply("404","Not Found"); } } failure_route[99] { delete_location_from_usrloc(); # I will write this function. route(1); } ==============